1. Technical Field
The present invention relates to a voltage detection apparatus for a battery system which includes a plurality of battery packs in each of which a plurality of unit cells made up of secondary batteries are connected together.
2. Background Art
An electric circuit for a hybrid vehicle includes a high-voltage system circuit for driving a motor in addition to a low-voltage system circuit for use in driving an engine. A battery pack is used as a power supply to the high-voltage system circuit. The battery pack includes a plurality of unit cells made up of secondary batteries which are connected in series.
In a power supply system of JP-A-2008-289234, a circuit board on which a cell controller is mounted is incorporated in a cell controller box. The cell controller is a high-voltage system circuit which is connected individually to single cells which configure a battery block via detection wire harnesses and is connected to a battery controller, which is a low-voltage system, through an insulation circuit via a communication harness. The detection wire harnesses are led out for battery pack blocks respectively from the circuit board on which the cell controller is mounted. The cell controller detects periodically terminal voltages of the cell batteries to store detection results and transmits the stored detection results to the battery controller when the cell controller receives an instruction from the battery controller.
In the related power supply system described above, since the detection wire harnesses are laid out from the cell batteries configuring the battery block to the circuit board on which the cell controller is mounted, it takes some labor hours to lay out the harnesses, which deteriorates workability. Moreover, when a crash occurs in the vehicle, the detection wire harnesses are disconnected to cause a short circuit, resulting in possibilities that the power supply system catches fire and starts to emit smoke.